Scanners are used to convert an image of a document or a photographic film into corresponding electrical signals. The electrical signals are, for example, then digitally stored and manipulated by a computer or other device.
U.S. Pat. No. 4,408,230 (K. Tamura et al.), issued on Oct. 4 1983, discloses a photosensor array device for use in a document contact scanner. The Tamura et al. patent discloses as prior art an arrangement comprising a fiber optic base that contacts the document to be read with a fiber optic bundle formed therein. Light reflected from the document being read passes through the fiber optic bundle and impinges a light sensing array formed on an opposing-side of the fiber optic base. The Tamura et al. patent states that such arrangement is not a practical solution, and describes a device wherein a metallic plate with predetermined spaced holes therein is sandwiched between the fiber optic base and a transparent insulating film mounting the light sensing array. The light sensing array receives light from the fiber optic bundle through the holes in the metallic plate.
U.S. Pat. No. 5,032,718 (S. Murakami), issued on Jul. 16, 1991, discloses a photosensor array and reader including hexagonal optical fiber bundles. The Murakami photosensor array is a similar array to that of FIG. 2 of U.S. Pat. No. 4,408,230 discussed above.
U.S. Pat. No. 4,942,481 (A. Yoshinouchi et al.), issued on Jul. 17, 1990, discloses a contact-tirpe image sensor for use in a document reader which is similar to the Tamura et al. patent described above. The Yoshinouchi image sensor comprises a substrate which contacts the document and includes a bundle of optical fibers embedded in, and passing through, the substrate. A light-absorbing substance is disposed along a fractional portion of the outer surfaces of the optical fibers in the area nearest the photodetectors. With such arrangement, light from a light source irradiates the document below the area of the light-absorbing substance, and light leakage from the fibers is absorbed in the area of the light-absorbing substance. Photodetectors are mounted on the substrate with a space therebetween to provide a predetermined modulation transfer function (MTF).
Contact scanners for scanning film differ in several ways which pose different design requirements. A first design requirement is that film contact scanners must include much higher resolution (about 10 times) than document contact scanners. This requirement makes many page (document) contact scanner techniques inadequate. A second design requirement is that film contact scanners are transmission devices which require that the film be illuminated from behind, whereas document contact scanners are reflection devices. This substantially changes the design criteria. A third design requirement is the realization that scratches in the film are a much more serious problem than with documents. Scratches are often ignored with document contact scanners. However, film contact scanners require careful design attention to deal with scratches. A fourth design requirement has to do with a realization that film is more fragile than paper documents. ? his requires more fragile handling of the film while avoiding contact therewith during the reading (scanning) process. Document contact scanners, on the other hand, are permitted to freely bring, for example, the paper document into contact with various surfaces of the document contact scanner.
Referring now to FIG. 1, there is shown a traditional prior art film scanner 10. The traditional film scanner 10 comprises an illumination source 12 (e.g., a lamp), illumination optics 14 for directing light from the illumination source 12 onto a film 16, collection optics 18 for collecting the light passing through the film and focusing an image of the film onto a light detector 19. The collection optics 18 are typically lenses which are necessary to re-focus the image of the film 16 onto a spaced-apart light detector 19. The light detector 19 comprises any suitable device such as a single photodetector, a linear photodetector array, or an area photodetector array.
U.S. Pat. No. 3,210,462 (T. Trott), issued on Oct. 5, 1965, discloses an electro-optical film-scanning system which is an alternative arrangement from that shown in FIG. 1. The disclosed film scanning system of Trott comprises a planar array of optical fibers and a scanning means. The optical fiber array has a flat end section adjacent the film and an arcuate end section adjacent the scanning means. The scanning means picks up light from each of the optical fibers in a sequence by rotating separate individual scanning elements. The prime purpose of the fiber optics is to convert the image of the scan line to a circular arc.
It is desirable to provide a contact-type film scanner which avoids unnecessary elements (e.g., the collection optics of FIG. 1), achieves scratch suppression in the film image, and provides both film flatness in the area of scanning and precise positioning of the film.